Supports for sintering additively manufactured parts

ABSTRACT

A method comprising depositing, in layers, a shrinking platform formed from a composite including metal particles embedded in a first matrix, depositing shrinking supports of the composite upon the shrinking platform, forming a separation clearance dividing at least one shrinking support into fragments, depositing, from the composite, a part upon the shrinking platform and shrinking supports, depositing a separation material intervening between the part and the shrinking supports, the separation material including a ceramic powder and a second matrix, and forming, from the shrinking platform, shrinking supports, separation material, and part, a portable platform assembly in a green state, wherein the shrinking support is configured to prevent the portable platform assembly from distorting from gravitational force during sintering of the metal particles of the assembly in a brown state, and wherein the ceramic powder of the separation material is configured to separate the shrinking support from the part following sintering.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/722,445, filed Oct. 2, 2017, entitled “SUPPORTS FOR SINTERINGADDITIVELY MANUFACTURED PARTS”, herein incorporated by reference in itsentirety. U.S. patent application Ser. No. 15/722,445 claims the benefitunder 35 U.S.C. § 119(e) of U.S. provisional application Ser. No.62/429,711, filed Dec. 2, 2016, entitled “SUPPORTS FOR SINTERINGADDITIVELY MANUFACTURED PARTS”; 62/430,902, filed Dec. 6, 2016, entitled“WARM SPOOL FEEDING FOR SINTERING ADDITIVELY MANUFACTURED PARTS”;62/442,395 filed Jan. 4, 2017, entitled “INTEGRATED DEPOSITION ANDDEBINDING OF ADDITIVE LAYERS OF SINTER-READY PARTS”; 62/480,331 filedMar. 31, 2017, entitled “SINTERING ADDITIVELY MANUFACTURED PARTS IN AFLUIDIZED BED”; 62/489,410 filed Apr. 24, 2017, entitled “SINTERINGADDITIVELY MANUFACTURED PARTS IN MICROWAVE OVEN”; 62/505,081 filed May11, 2017, entitled “RAPID DEBINDING VIA INTERNAL FLUID CHANNELS”;62/519,138 filed Jun. 13, 2017, entitled “COMPENSATING FORBINDER-INTERNAL STRESSES IN SINTERABLE 3D PRINTED PARTS”; and 62/545,966filed Aug. 15, 2017, entitled “BUBBLE REMEDIATION IN 3D PRINTING OFMETAL POWDER IN SOLUBLE BINDER FEEDSTOCK”, the disclosures of which areherein incorporated by reference in their entireties.

FIELD

Aspects relate to three dimensional printing of composite metal orceramic materials.

BACKGROUND

“Three dimensional printing” as an art includes various methods forproducing metal parts.

In 3D printing, in general, unsupported spans as well as overhanging orcantilevered portions of a part may require removable and/or solubleand/or dispersing supports underneath to provide a facing surface fordeposition or to resist deformation during post-processing.

SUMMARY

According to a first aspect of the embodiments of the present invention,a method of reducing distortion in an additively manufactured partincludes forming a shrinking platform of successive layers of composite,the composite including a metal particulate filler in a debindablematrix. The debindable matrix may include different components so as tobe a one or two stage binder. Shrinking supports are formed of the samecomposite above the shrinking platform. A desired part of the samecomposite is formed upon the shrinking platform and shrinking supports,substantially horizontal portions (e.g., overhangs, bridges, largeradius arches) of the desired part being vertically supported by theshrinking platform (e.g., directly, via the shrinking supports, or via arelease layer). A sliding release layer is formed below the shrinkingplatform of equal or larger surface area than a bottom of the shrinkingplatform (e.g., as shown in FIG. 4) that reduces lateral resistancebetween the shrinking platform and an underlying surface (e.g., such asa build platform or a tray for sintering). The matrix is deboundsufficient to form a shape-retaining brown part assembly (e.g.,including a sparse lattice of remaining binder to hold the shape)including the shrinking platform, shrinking supports, and desired part.The shape-retaining brown part assembly formed from the same compositeis heated to shrink all of the shrinking platform, the shrinkingsupports, and the desired part together at a same rate as neighboringmetal particles throughout the shape-retaining brown part assemblyundergo atomic diffusion. According, uniform shrinking and the slidingrelease layer reduce distortion.

An apparatus of similar advantage may include a print head that depositsthe shrinking platform, the shrinking supports, and the desired part, asecond printhead that forms the sliding release layer, a debinding washthat debinds the shape-retaining brown part assembly, and a sinteringoven to heat and shrink the shrinking platform, the shrinking supports,and the desired part together at a same rate.

Optionally, an open cell structure including interconnections among cellchambers is deposited in at least one of the shrinking platform, theshrinking supports, and the desired part; and a fluid debinder ispenetrated into the open cell structure to debind the matrix from withinthe open cell structure. Additionally, or alternatively, the shrinkingplatform, shrinking supports, and desired part may be formed tosubstantially align a centroid of the combined shrinking platform andconnected shrinking supports with the centroid of the part. Furtheradditionally or in the alternative, the shrinking supports may beinterconnected to a side of the desired part by forming separableattachment protrusions of the same composite between the shrinkingsupports and the side of the desired part. Still further additionally orin the alternative, a lateral support shell may be formed of the samecomposite following a lateral contour of the desired part, and thelateral support shell may be connected to the lateral contour of thedesired part by forming separable attachment protrusions of the samecomposite between the lateral support shell and the desired part.

Further optionally, soluble support structures of the debindable matrixmay be formed, without the metal particulate filler, that resistdownward forces during the forming of the desired part, and the matrixdebound sufficient to dissolve the soluble support structures beforeheating the shape-retaining brown part assembly. Alternatively, or inaddition, soluble support structures of a release composite may beformed, the release composite including a ceramic particulate filler andthe debindable matrix, the soluble support structures resisting downwardforces during the forming of the desired part. Before heating theshape-retaining brown part assembly, the matrix may be deboundsufficient to form a shape-retaining brown part assembly including theshrinking platform, shrinking supports, and desired part, and todissolve the matrix of the soluble support structures.

Additionally, or in the alternative, the underlying surface may includea portable build plate. In this case, the shrinking platform may beformed above the portable build plate, and the sliding release layerformed below the shrinking platform and above the portable build platewith a release composite including a ceramic particulate and thedebindable matrix. The shape-retaining brown part assembly may besintered during the heating. The build plate, sliding release layer, andshape-retaining brown part assembly may be kept together as a unitduring the debinding and during the sintering. After sintering, thebuild plate, sliding release layer, shrinking platform, and shrinkingsupports may be separated from the desired part.

Optionally, part release layers may be formed between the shrinkingsupports and the desired part with a release composite including aceramic particulate filler and the debindable matrix, and theshape-retaining brown part assembly sintered during the heating. Thepart release layers and shape-retaining brown part assembly may be kepttogether as a unit during the debinding and during the sintering. Aftersintering, separating the part release layers, shrinking platform, andshrinking supports may be separated from the desired part. In this case,an open cell structure including interconnections among cell chambers inthe shrinking supports may be deposited, and a fluid debinder may bepenetrated into the open cell structure to debind the matrix from withinthe open cell structure.

According to another aspect of the embodiments of the present invention,a method of reducing distortion in an additively manufactured partincludes depositing, in successive layers, a shrinking platform formedfrom a composite, the composite including a metal particulate filler ina debindable matrix, and depositing shrinking supports of the samecomposite and above the shrinking platform. An open cell structureincluding interconnections is deposited among cell chambers in theshrinking supports. From the same composite, a desired part is depositedupon the shrinking platform and shrinking supports. The shrinkingplatform, shrinking supports, and desired part are exposed to a fluiddebinder to form a shape-retaining brown part assembly. The fluiddebinder is penetrated into the open cell structure to debind the matrixfrom within the open cell structure. The shape-retaining brown partassembly is sintered to shrink at a rate common throughout theshape-retaining brown part assembly.

Optionally, a sliding release layer is deposited below the shrinkingplatform of equal or larger surface area than a bottom of the shrinkingplatform that reduces lateral resistance between the shrinking platformand an underlying surface. Additionally, or in the alternative, partrelease layers are deposited between the shrinking supports and thedesired part with a release composite including a ceramic particulatefiller and the debindable matrix, and the part release layers andshape-retaining brown part assembly are kept together as a unit duringthe exposing and during the sintering. After sintering, the part releaselayers, shrinking platform, and shrinking supports are separated fromthe desired part. Further optionally, as shown in, e.g., FIGS. 8-10,vertical gaps without release composite are formed between shrinkingsupports and the desired part where a vertical surface of a shrinkingsupport opposes an adjacent wall of the desired part.

Alternatively, or in addition, as shown in, e.g., FIGS. 8-10, a lateralsupport shell block is deposited having a large cell interior, havingcells with cell cavities wider than a thickest wall within the lateralsupport shell block, to assist in diffusing and penetrating debindingfluid into the support. Further alternatively, or in addition, theshrinking supports may be interconnected to a side of the desired partby forming separable attachment protrusions of the same compositebetween the shrinking supports and the side of the desired part.

Further optionally, as shown in, e.g., FIGS. 8-10, a lateral supportshell of the same composite as the shrinking supports may be depositedto follow a lateral contour of the desired part. In this case, thelateral support shell may be connected to the lateral contour of thedesired part by forming separable attachment protrusions of the samecomposite between the lateral support shell and the desired part.Alternatively, or in addition, at least one of the shrinking platform,the lateral support shell and the desired part may be deposited withinterconnections between internal chambers, and a fluid debinder may bepenetrated via the interconnections into the internal chambers to debindthe matrix from within the open cell structure. The shrinking platform,shrinking supports, and desired part may be deposited to substantiallyalign a centroid of the combined shrinking platform and connectedshrinking supports with the centroid of the part.

According to another aspect of the embodiments of the present invention,a method of reducing distortion in an additively manufactured partincludes depositing, in successive layers, a shrinking platform formedfrom a composite, the composite including a metal particulate filler ina debindable matrix. Shrinking supports of the same composite may bedeposited above the shrinking platform. As shown in, e.g., FIGS. 8-10,among the shrinking supports, parting lines as separation clearances maybe formed dividing the shrinking supports into fragments separable alongthe separation clearances. From the same composite, a desired part maybe shaped upon the shrinking platform and shrinking supports. The matrixmay be debound sufficient to form a shape-retaining brown part assemblyincluding the shrinking platform, shrinking support columns, and desiredpart. The shape-retaining brown part assembly may be sintered to shrinkat a rate uniform throughout the shape-retaining brown part assembly.The shrinking supports may be separated into fragments along theseparation clearances, and the fragments may be separated from thedesired part.

Optionally, one or more separation clearances are formed as verticalclearance separating neighboring support columns and extending forsubstantially an height of the neighboring support columns, and furthercomprising, and the neighboring support columns are separated from oneanother along the vertical clearances. Alternatively, or in addition,within a cavity of the desired part, interior shrinking supports areformed from the same composite. Among the interior shrinking supports,parting lines may be formed as separation clearances dividing theinterior shrinking supports into subsection fragments separable alongthe separation clearances. The subsection fragments may be separatedfrom one another along the separation clearances.

Alternatively, or in addition, the fragments are formed as blocksseparable from one another along a separation clearance contiguouswithin a plane intersecting the shrinking supports. A lateral supportshell of the same composite as the shrinking supports may be formed tofollow a lateral contour of the desired part. Optionally, the lateralsupport shell may be connected to the lateral contour of the desiredpart by forming separable attachment protrusions of the same compositebetween the lateral support shell and the desired part. Furtheroptionally, in the lateral support shell, parting lines may be formeddividing the lateral support shell into shell fragments separable alongthe parting lines. The matrix may be debound sufficient to form ashape-retaining brown part assembly including the shrinking platform,shrinking support columns, lateral support shell, and desired part. Thelateral support shell may be separated into the shell fragments alongthe parting lines. The shell fragments may be separated from the desiredpart.

Further optionally, at least one of the shrinking platform, theshrinking supports, and the desired part may be deposited withinterconnections between internal chambers, and a fluid debinderpenetrated via the interconnections into the internal chambers to debindthe matrix from within the open cell structure. Alternatively, or inaddition, soluble support structures of the debindable matrix withoutthe metal particulate filler may be formed that resist downward forcesduring the forming of the desired part, and the matrix deboundsufficient to dissolve the soluble support structures before sinteringthe shape-retaining brown part assembly.

Still further optionally, a sliding release layer may be formed belowthe shrinking platform of equal or larger surface area than a bottom ofthe shrinking platform that reduces lateral resistance between theshrinking platform and build plate, and the shrinking platform may beformed above the portable build plate. The sliding release layer may beformed below the shrinking platform and above the portable build platewith a release composite including a ceramic particulate and thedebindable matrix, the build plate, sliding release layers andshape-retaining brown part assembly may be kept together as a unitduring the debinding and during the sintering.

Further alternatively or in addition, part release layers may be formedbetween the shrinking supports and the desired part with a releasecomposite including a ceramic particulate filler and the debindablematrix, and the part release layers and shape-retaining brown partassembly may be kept together as a unit during the debinding and duringthe sintering. After sintering, the part release layers, shrinkingplatform, and shrinking supports may be separated from the desired part.

At least one aspect in accordance with the present invention is directedto a method of reducing distortion in an additively manufactured part,comprising depositing, in successive layers, a shrinking platform formedfrom a composite, the composite including metal particles embedded in afirst matrix, depositing shrinking supports of the composite upon theshrinking platform, forming, in at least one shrinking support, aseparation clearance dividing the at least one shrinking support intofragments, depositing, from the composite, a part upon the shrinkingplatform and shrinking supports, depositing a separation materialintervening between the part and the shrinking supports, the separationmaterial including a ceramic powder and a second matrix, and forming,from the shrinking platform, shrinking supports, separation material,and part, a portable platform assembly in a green state, wherein theshrinking support is configured to prevent the portable platformassembly from distorting from gravitational force during sintering ofthe metal particles of the portable platform assembly in a brown state,and wherein the ceramic powder of the separation material is configuredto separate the shrinking support from the part following sintering.

According to one embodiment, the shrinking platform interconnects theshrinking supports with one another, and the method further comprisesmaintaining, with the first matrix and second matrix, a shape of theportable platform assembly during deposition, debinding the first matrixin the portable platform assembly from the green state to the brownstate, in a first common chamber, transporting the portable platformassembly in the brown state to a second common chamber for sintering,sintering the portable platform assembly in the brown state to shrink ata rate uniform throughout as neighboring metal particles throughout theshape-retaining brown part assembly undergo atomic diffusion, and duringsintering in the second common chamber, decomposing the second matrix toleave the ceramic powder loose via the heat of the sintering,maintaining, with the first matrix, a shape of the portable platformassembly during at least part of the sintering, and maintaining, withthe ceramic powder, the shrinking supports separate from the part.

According to one embodiment, the separation clearance is formed as avertical clearance separating neighboring shrinking supports andextending for substantially a height of the neighboring shrinkingsupports, and the method further comprises separating the neighboringshrinking supports from one another along the vertical clearance. In oneembodiment, the first matrix and the second matrix are at leastpartially debindable by a common debinder. In another embodiment,forming the separation clearance comprises forming the fragments asblocks separable from one another along the separation clearancecontiguous within a plane intersecting the shrinking supports. In oneembodiment, depositing shrinking supports comprises forming a lateralsupport shell of the composite as the shrinking supports to follow alateral contour of the part.

According to another embodiment, the method further comprises connectingthe lateral support shell to the lateral contour of the part by formingseparable attachment protrusions of the composite between the lateralsupport shell and the part. In one embodiment, the method furthercomprises dividing the lateral support shell into shell fragments,debinding the first matrix sufficient to form a portable assembly in thebrown state including the shrinking platform, shrinking supports,lateral support shell, and part, separating the lateral support shellinto the shell fragments, and separating the shell fragments from thepart. In one embodiment, the method further comprises depositing theseparation material to intervene at a non-horizontal surface of the partopposing a surface of the shrinking supports, the non-horizontal surfaceof the part including at least one of a vertical surface, a curvedsurface, and a surface angled with respect to horizontal. In anotherembodiment, the method further comprises providing a sliding powderlayer below the shrinking platform, of equal or larger surface area thana bottom of the shrinking platform, the sliding powder layer configuredto reduce lateral resistance between the shrinking platform and anunderlying surface during sintering.

Another aspect in accordance with the present invention is directed to amethod of reducing distortion in an additively manufactured part,comprising depositing, in successive layers, a shrinking platform formedfrom a composite, the composite including metal particles, a firstbinder component, and a second binder component, depositing, from thecomposite, a part supported by the shrinking platform, the shrinkingplatform forming a foundation that holds the part and is configured,during shrinking of the composite, to prevent movement of the shrinkingplatform versus the part, depositing a first shrinking support of thecomposite upon a first portion of the part and supporting a secondportion of the part, depositing a separation material interveningbetween the part and the first shrinking support, the separationmaterial including a ceramic powder and a third binder component,wherein the third binder component is responsive to a same debinder asthe first binder component, forming, in the first shrinking support, aseparation clearance dividing the first shrinking support into fragmentsseparable along the separation clearance, and forming the shrinkingplatform, first shrinking support, separation material, and part as aportable platform assembly in a green state, wherein the first bindercomponent and third binder component are configured to maintain a shapeof the portable platform assembly during depositing of the portableplatform assembly, wherein the first shrinking support is configured toprevent the portable platform assembly from distorting fromgravitational force during sintering of the metal particles of theportable platform assembly in a brown state, and wherein the separationmaterial is configured to separate the first shrinking support from thepart during sintering and powderize to permit the first shrinkingsupport to be removed from the part after sintering.

According to one embodiment, the method further comprises depositingsecond shrinking supports of the composite upon the shrinking platform,the shrinking platform interconnecting the shrinking supports with oneanother, and depositing the separation material intervening between thepart and the second shrinking supports, wherein the second shrinkingsupports are included in the portable platform assembly in the greenstate, and the ceramic powder of the separation material is configuredto separate the second shrinking support from the part followingsintering. In one embodiment, the method further comprises depositingthe separation material intervening directly between the part and theshrinking platform, wherein the ceramic powder of the separationmaterial is configured to separate the part from the shrinking platformfollowing sintering.

According to another embodiment, the method further comprisesmaintaining, with the first binder component and second bindercomponent, a shape of the portable platform assembly during deposition,debinding the first binder component in the platform assembly from agreen state to a brown state, in a first common chamber, transportingthe portable platform assembly in the brown state to a second commonchamber, sintering, in the second common chamber, the portable platformassembly in the brown state to shrink at a rate uniform throughout asneighboring metal particles throughout the shape-retaining brown partassembly undergo atomic diffusion and the second binder decomposes inthe heat of sintering, and decomposing the third binder component toleave the ceramic powder loose in the second common chamber.

According to one embodiment, the separation clearance is formed as avertical clearance extending for substantially a height of the firstshrinking support, and the method further comprises separating thefragments from one another along the vertical clearances. In oneembodiment, forming the separation clearance comprises forming thefragments as blocks separable from one another along a separationclearance contiguous within a plane intersecting the first shrinkingsupport. In another embodiment, depositing the first shrinking supportcomprises forming a lateral support shell of the same composite as thefirst shrinking support to follow a lateral contour of the part. In oneembodiment, the method further comprises dividing the lateral supportshell into shell fragments, and separating the shell fragments from thepart.

According to another embodiment, depositing the separation materialcomprises depositing the separation material to intervene at anon-horizontal surface of the part opposing a surface of the firstshrinking support, the non-horizontal surface of the part including atleast one of a vertical surface, a curved surface, and a surface angledwith respect to horizontal. In one embodiment, the method furthercomprises providing a sliding powder layer below the shrinking platform,of equal or larger surface area than a bottom of the shrinking platform,the sliding powder layer configured to reduce lateral resistance betweenthe shrinking platform and an underlying surface during sintering.

At least one aspect in accordance with the present invention is directedto a method of reducing distortion in an additively manufactured part,comprising feeding a composite including metal particles, a first binderand a second binder, feeding a separation material including ceramicpowder and a third binder, depositing a portable platform assemblyformed from the composite in a green state, the portable platformassembly including a shrinking platform, first shrinking supports,second shrinking supports, separation material and a part, the shrinkingplatform interconnecting the first shrinking supports with one another,the part deposited upon the first shrinking supports, the secondshrinking supports supporting an upper portion of the part upon a lowerportion of the part, and the separation material separating the partfrom the first shrinking supports and the second shrinking supports,maintaining a shape of the portable platform assembly during depositionwith the first binder, second binder, and third binder, forming aseparation clearance during deposition dividing at least one of thesecond shrinking supports into fragments, debinding the first binder todebind the platform assembly from a green state to a brown state, andsintering the platform assembly in the brown state to shrink at a rateuniform throughout the portable platform assembly as interconnected bythe shrinking platform, and to decompose the second binder and the thirdbinder, wherein the relative shape of the platform assembly ismaintained versus gravitational force by the first shrinking supportsand the second shrinking supports, and wherein the third binder isdecomposed during sintering to powderize the separation material leavinga loose ceramic powder separating the part from the first shrinkingsupports and the second shrinking supports.

According to one embodiment, the method further comprises depositing theseparation material in the portable platform assembly interveningdirectly between the part and the shrinking platform, wherein the looseceramic powder separates the part from the shrinking platform followingsintering. In one embodiment, forming the separation clearance comprisesforming the separation clearance as a vertical clearance extending forsubstantially a height of the at least one second shrinking support, andthe method further comprises separating the fragments from one anotheralong the vertical clearances. In another embodiment, forming theseparation clearance comprises forming the fragments as blocks separablefrom one another along the separation clearance contiguous within aplane intersecting the first shrinking support. In one embodiment, themethod further comprises forming a lateral support shell of the samecomposite as the first shrinking support to follow a lateral contour ofthe part.

According to another embodiment, the method further comprises dividingthe lateral support shell into shell fragments, and separating the shellfragments from the part. In one embodiment, the method further comprisesdepositing the separation material to intervene at a non-horizontalsurface of the part opposing a surface of the first shrinking support,the non-horizontal surface of the part including at least one of avertical surface, a curved surface, and a surface angled with respect tohorizontal. In another embodiment, the method further comprisesproviding a sliding powder layer below the shrinking platform, of equalor larger surface area than a bottom of the shrinking platform, thatreduces lateral resistance between the shrinking platform and anunderlying surface during sintering.

According to one embodiment, the underlying surface comprises a portablebuild plate, and the method further comprises forming the shrinkingplatform above the portable build plate, forming the sliding powderlayer below the shrinking platform and above the portable build platewith the release material, and keeping the portable platform assemblytogether with the portable build plate as a unit during deposition,debinding, and sintering. In one embodiment, the metal particles in thecomposite are distributed in at least two sizes.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic representation of three-dimensional metal printer.

FIG. 2 is a block diagram and schematic representation of a threedimensional printer system.

FIG. 3 is a flowchart describing the overall operation of the 3D printerof FIG. 2.

FIG. 4 is a schematic representation of a 3D printing system, part, andprocess in which sintering supports (e.g. shrinking supports) areprovided.

FIGS. 5A-5D are schematic sections through the diagram of FIG. 4.

FIG. 6 is a schematic representation of an alternative 3D printingsystem, part, and process to that of FIG. 4.

FIG. 7 is a schematic representation of one exemplary process ofprinting, debinding, sintering, and support removal with separationand/or release layers, green body supports and/or sintering or shrinkingsupports.

FIG. 8 is an schematic representation of an additional alternative 3Dprinting system, part, and process to that of FIG. 4.

FIG. 9 is an schematic representation of an additional alternative 3Dprinting system, part, and process to that of FIG. 4.

FIG. 10 is a top view of a sintered assembly of the 3D printing system,part, and process of FIG. 4, showing parting lines for removing supportshells or sintering or shrinking supports.

FIG. 11 is a top view of a sintered assembly of an alternative 3Dprinting system, part, and process to that of FIG. 4, showing partinglines for removing support shells or sintering or shrinking supports.

FIGS. 12 and 13 are 3D views of the part schematically depicted FIGS. 8and 9.

DETAILED DESCRIPTION

This patent application incorporates the following disclosures byreference in their entireties: U.S. Patent Application Ser. Nos.61/804,235; 61/815,531; 61/831,600; 61/847,113; 61/878,029; 61/880,129;61/881,946; 61/883,440; 61/902,256; 61/907,431; and 62/080,890; Ser.Nos. 14/222,318; 14/297,437; and 14/333,881, may be referred to hereinas “Composite Filament Fabrication patent applications” or “CFF patentapplications”. Although the present disclosure discusses various metalor ceramic 3D printing systems, at least the mechanical and electricalmotion, control, and sensor systems of the CFF patent applications maybe used as discussed herein. In addition, U.S. Pat. Nos. 6,202,734;5,337,961; 5,257,657; 5,598,200; 8,523,331; 8,721,032, and U.S. PatentPublication No. 20150273577, are incorporated herein by reference intheir entireties.

In 3D printing, in general, overhanging or jutting portions of a partmay require removable and/or soluble and/or dispersing supportsunderneath to provide a facing surface for deposition. In metalprinting, in part because metal is particularly dense (e.g., heavy),removable and/or soluble and/or dispersing supports may also be helpfulto prevent deformation, sagging, during mid- or post-processing—forexample, to preserve shape vs. drooping or sagging in potentiallydeforming environments like high heat.

Printing a sinterable part using a 3D printing material including abinder and a ceramic or metal sintering material is aided by supportstructures, able to resist the downward pressure of, e.g., extrusion,and locate the deposited bead or deposition in space. A release layerintervening between the support structures and the part includes ahigher melting temperature material—ceramic or high temperature metalfor example, optionally deposited with a similar (primary) matrix orbinder component to the model material. Beneath the release layer, themodel material as the part is used for support structures, promoting thesame compaction/densification. This tends to mean the part and thesupports will shrink uniformly, maintaining dimensional accuracy of thepart. At the bottom of the support, a release layer may also be printed.In addition, the support structures may be printed sections with releaselayers, such that the final sintered support structures will readilybreak into smaller subsections for easy removal, optionally in thepresence of mechanical or other agitation. In this way, a large supportstructure can be removed from an internal cavity via a substantiallysmaller hole. In addition, or in the alternative, a further method ofsupport is to print soluble support material that is removed in thedebinding process. For catalytic debind, this may be Delrin (POM)material. One method to promote uniform shrinking is to print a ceramicrelease layer as the bottom most layer in the part. On top of thesliding release layer (analogous to microscopic ball bearings) a thinsheet of metal—e.g., a raft—may be printed that will uniformly shrinkwith the part, and provide a “shrinking platform” to hold the part andthe related support materials in relative position during the shrinkingprocess. Optionally staples or tacks, e.g., attachment points, connectand interconnect the model material portions being printed.

The printer(s) of FIGS. 1-9, with at least two print heads 18, 10 and/orprinting techniques, deposit with one head a composite materialincluding a debinder and dispersed spheres or powder 18 (thermoplasticor curing), used for printing both a part and support structures, andwith a second head 18 a (shown in FIGS. 4-9) deposits release orseparation material. Optionally a third head and/or fourth head includea green body support head 18 b and/or a continuous fiber deposition head10. A fiber reinforced composite filament 2 (also referred to herein ascontinuous core reinforced filament) may be substantially void free andinclude a polymer or resin that coats, permeates or impregnates aninternal continuous single core or multistrand core. It should be notedthat although the print head 18, 18 a, 18 b are shown as extrusion printheads, “fill material print head” 18, 18 a, 18 b as used herein mayinclude optical or UV curing, heat fusion or sintering, or “polyjet”,liquid, colloid, suspension or powder jetting devices—not shown—fordepositing fill material, so long as the other functional requirementsdescribed herein are met (e.g., green body material supports printingvs. gravity or printing forces, sintering or shrinking supports the partvs. gravity and promote uniform shrinking via atomic diffusion duringsintering, and release or separation materials substantially retainshape through debinding stems but become readily removable, dispersed,powderized or the like after sintering).

Although FIGS. 1-9 in general show a Cartesian arrangement forrelatively moving each print head in 3 orthogonal translationdirections, other arrangements are considered within the scope of, andexpressly described by, a drive system or drive or motorized drive thatmay relatively move a print head and a build plate supporting a 3Dprinted part in at least three degrees of freedom (i.e., in four or moredegrees of freedom as well). For example, for three degrees of freedom,a delta, parallel robot structure may use three parallelogram armsconnected to universal joints at the base, optionally to maintain anorientation of the print head (e.g., three motorized degrees of freedomamong the print head and build plate) or to change the orientation ofthe print head (e.g., four or higher degrees of freedom among the printhead and build plate). As another example, the print head may be mountedon a robotic arm having three, four, five, six, or higher degrees offreedom; and/or the build platform may rotate, translate in threedimensions, or be spun.

A fiber reinforced composite filament, when used, is fed, dragged,and/or pulled through a conduit nozzle optionally heated to a controlledtemperature selected for the matrix material to maintain a predeterminedviscosity, force of adhesion of bonded ranks, melting properties, and/orsurface finish. After the matrix material or polymer of the fiberreinforced filament is substantially melted, the continuous corereinforced filament is applied onto a build platen 16 to buildsuccessive layers of a part 14 to form a three dimensional structure.The relative position and/or orientation of the build platen 16 andprint heads 18, 18 a, 18 b, and/or 10 are controlled by a controller 20to deposit each material described herein in the desired location anddirection. A driven roller set 42, 40 may drive a continuous filamentalong a clearance fit zone that prevents buckling of filament. In athreading or stitching process, the melted matrix material and the axialfiber strands of the filament may be pressed into the part and/or intothe swaths below, at times with axial compression. As the build platen16 and print head(s) are translated with respect to one another, the endof the filament contacts an ironing lip and be subsequently continuallyironed in a transverse pressure zone to form bonded ranks or compositeswaths in the part 14.

With reference to FIG. 1, each of the printheads 18, 18 a, 18 b, 10 maybe mounted on the same linear guide or different linear guides oractuators such that the X, Y motorized mechanism of the printer movesthem in unison. As shown, each extrusion printhead 18, 18 a, 18 b mayinclude an extrusion nozzle with melt zone or melt reservoir, a heater,a high thermal gradient zone formed by a thermal resistor or spacer(optionally an air gap), and/or a Teflon or PTFE tube. A 1.75-1.8 mm; 3mm; or larger or smaller thermoplastic filament is driven through, e.g.,direct drive or a Bowden tube provides extrusion back pressure in themelt reservoir.

FIG. 2 depicts a block diagram and control system of the threedimensional printer which controls the mechanisms, sensors, andactuators therein, and executes instructions to perform the controlprofiles depicted in and processes described herein. A printer isdepicted in schematic form to show possible configurations of e.g.,three commanded motors 116, 118, and 120. It should be noted that thisprinter may include a compound assembly of printheads 18, 18 a, 18 b,and/or 10.

As depicted in FIG. 2, the three-dimensional printer 3001 includes acontroller 20 which is operatively connected to the fiber head heater715, the fiber filament drive 42 and the plurality of actuators 116,118, 120, wherein the controller 20 executes instructions which causethe filament drive to deposit and/or compress fiber into the part. Theinstructions are held in flash memory and executed in RAM (not shown;may be embedded in the controller 20). An actuator 114 for applying aspray coat, as discussed herein, may also be connected to the controller20. In addition to the fiber drive 42, respective filament feeds 1830(e.g., up to one each for heads 18, 18 a, and/or 18 b) may be controlledby the controller 20 to supply the extrusion printhead 1800. A printheadboard 110, optionally mounted on the compound printhead and movingtherewith and connected to the main controller 20 via ribbon cable,breaks out certain inputs and outputs. The temperature of the ironingtip 726 may be monitored by the controller 20 by a thermistor orthermocouple 102; and the temperature of the heater block holding nozzle1802 of any companion extrusion printhead 1800 may be measured byrespective thermistors or thermocouples 1832. A heater 715 for heatingthe ironing tip 726 and respective heater 1806 for heating respectiveextrusion nozzles 1802 are controlled by the controller 20. Heat sinkfan(s) 106 and a part fan(s) 108, each for cooling, may be sharedbetween the printheads, or independently provided, and controlled by thecontroller 20. A rangefinder 15 is also monitored by the controller 20.The cutter 8 actuator, which may be a servomotor, a solenoid, orequivalent, is also operatively connected. A lifter motor for liftingone or any printhead away from the part (e.g., to control dripping,scraping, or rubbing) may also be controlled. Limit switches 112 fordetecting when the actuators 116, 118, 120 have reached the end of theirproper travel range are also monitored by the controller 20.

As depicted in FIG. 2, an additional breakout board 122, which mayinclude a separate microcontroller, provides user interface andconnectivity to the controller 20. An 802.11 Wi-Fi transceiver connectsthe controller to a local wireless network and to the Internet at largeand sends and receives remote inputs, commands, and control parameters.A touch screen display panel 128 provides user feedback and acceptsinputs, commands, and control parameters from the user. Flash memory 126and RAM 130 store programs and active instructions for the userinterface microcontroller and the controller 20.

FIG. 3 depicts a flowchart showing a printing operation of the printers1000 in FIGS. 1-9. FIG. 3 describes, as a coupled functionality, controlroutines that may be carried out to alternately and in combination usethe co-mounted FFF extrusion head(s) 18, 18 a, and/or 18 b and a fiberreinforced filament printing head as in the CFF patent applications.

In FIG. 3, at the initiation of printing, the controller 20 determinesin step S10 whether the next segment to be printed is a fiber segment ornot, and routes the process to S12 in the case of a fiber filamentsegment to be printed and to step S14 in the case of other segments,including e.g., base, fill, or coatings. After each or either ofroutines S12 and S14 have completed a segment, the routine of FIG. 3checks for slice completion at step S16, and if segments remain withinthe slice, increments to the next planned segment and continues thedetermination and printing of fiber segments and/or non-fiber segmentsat step S18. Similarly, after slice completion at step S16, if slicesremain at step S20, the routine increments at step S22 to the nextplanned slice and continues the determination and printing of fibersegments and/or non-fiber segments. “Segment” as used herein correspondsto “toolpath” and “trajectory”, and means a linear row, road, or rankhaving a beginning and an end, which may be open or closed, a line, aloop, curved, straight, etc. A segment begins when a printhead begins acontinuous deposit of material, and terminates when the printhead stopsdepositing. A “slice” is a single layer or lamina to be printed in the3D printer, and a slice may include one segment, many segments, latticefill of cells, different materials, and/or a combination offiber-embedded filament segments and pure polymer segments. A “part”includes a plurality of slices to build up the part. FIG. 3's controlroutine permits dual-mode printing with one, two, or more (e.g., four)different printheads, including the compound printheads 18, 18 a, 18 b,and/or 10.

All of the printed structures previously discussed may be embeddedwithin a printed article during a printing process, as discussed herein,expressly including reinforced fiber structures of any kind, sparse,dense, concentric, quasi-isotropic or otherwise as well as fill materialor plain resin structures. In addition, in all cases discussed withrespect to embedding in a part, structures printed by fill materialheads 18, 18 a, 18 b using thermoplastic extrusion deposition may be ineach case replaced with soluble material (e.g., soluble thermoplastic orsalt) to form a soluble preform which may form a printing substrate forpart printing and then removed. All continuous fiber structuresdiscussed herein, e.g., sandwich panels, shells, walls, reinforcementsurrounding holes or features, etc., may be part of a continuous fiberreinforced part.

Using the 3D printer herein discussed with reference to FIGS. 1-9inclusive, which may deposit either fill material (composite with adebindable matrix containing metal, ceramic, and/or fibers), soluble(e.g., “soluble” also including, in some cases, debindable by thermal,pyrolytic or catalytic process) material, or continuous fiber, thereinforcing fiber may be additive[0034] With reference to FIGS. 1 and 2,each of the printheads 18 and 10 are mounted on the same linear guidesuch that the X, Y motorized mechanism 116, 118 of the printer 1000moves them in unison. A 1.75-1.8 mm; 3 mm or larger or smaller metalfilament 10 b may be driven through, e.g., direct drive or a Bowden tubethat may provide extrusion back pressure in a melt reservoir 10 a orcrucible.

Commercially valuable metals suitable for printing include aluminum,titanium and/or stainless steel as well as other metals resistant tooxidation at both high and low temperatures (e.g., amorphous metal,glassy metal or metallic glass).

One form of post-processing is sintering. By molding or 3D printing asdescribed herein, a green body may be formed from an appropriatematerial, including a binder or binders and a powdered or spherizedmetal or ceramic (of uniform or preferably distributed particle orsphere sizes). A brown body may be formed from the green body byremoving one or more binders (using a solvent, catalysis, pyrolysis).The brown body may retain its shape and resist impact better than thegreen body due to remelting of a remaining binder. When the brown bodyis sintered at high temperature and/or pressure, remaining binder maypyrolise away, and the brown body uniformly contracts as it sinters. Thesintering may take place in an inert gas, a reducing gas, a reactinggas, or a vacuum. Application of heat (and optionally) pressureeliminates internal pores, voids and microporosity between and withinthe metal or ceramic beads through at least diffusion bonding and/oratomic diffusion. Supporting material, either the same or different frommodel material, supports the part being printed, post-processed, orsintered versus the deposition force of printing itself and/or versusgravity, particularly for unsupported straight or low-angle spans orcantilevers.

As noted, printing a part is aided by the support structures, able toresist the downward pressure of, e.g., extrusion, and locate thedeposited bead or deposition in space. As discussed herein a releaselayer includes in a higher melting temperature material—ceramic forexample, optionally deposited via similar (primary) matrix component tothe model material. Beneath the release layer, the same (metal) materialis used as the part, promoting the same compaction/densification. Thistends to mean the part and the supports will shrink uniformly,maintaining dimensional accuracy of the part. At the bottom of thesupport, a release layer may also be printed. In addition, the supportstructures may be printed sections with release layers, such that thefinal sintered support structures will readily break into smallersubsections for easy removal, optionally in the presence of mechanicalor other agitation. In this way, a large support structure can beremoved from an internal cavity via a substantially smaller hole. Inaddition, or in the alternative, a further method of support is to printsoluble support material that is removed in the debinding process. Forcatalytic debind, this may be Delrin (POM) material. One method topromote uniform shrinking is to print a ceramic release layer as thebottom most layer in the part. On top of the sliding release layer(analogous to microscopic ball bearings) a thin sheet of metal—e.g., araft—may be printed that will uniformly shrink with the part, andprovide a “shrinking platform” to hold the part and the related supportmaterials in relative position during the shrinking process. Optionallystaples or tacks, e.g., attachment points, connect and interconnect themodel material portions being printed.

FIGS. 4 through 7 show, in schematic form, additional explanation ofrelevant processes, structures, materials, and systems. As shown inFIGS. 4-7, a 3D printer suitable for the deposition phase of the processmay include one, two, three, or more deposition heads for depositingmodel material and supports (as well as, e.g., a continuous compositedeposition head). As shown in FIG. 4, a model material deposition head18 deposits a composite material including metal or ceramic spherizedpowder as well as a meltable or matrix of binding polymers, waxes,and/or other utility components. In the model material deposition head18, the process may use a low-diameter filament (e.g., 1-4 mm) as bothmaterial supply and back pressure for extrusion. In this case, the modelmaterial extrusion filament may be stiff, yet reasonably pliable assupplied (e.g., 0.1-3.0 GPa flexural modulus) and reasonably viscouswhen fluidized (e.g., melt or dynamic viscosity of 100-10,000 Pa·s,preferably 300-1000 Pa·s) in order to support bridging while printingacross gaps or spans, even absent green body supports or sintering(i.e., shrinking) supports below.

In the 3D printer and exemplary part shown in FIG. 4, a separation orrelease material deposition head 18-S and a green body support materialdeposition head 18-G may additionally be supported to move in at leastthree relative degrees of freedom with respect to the part P1 beingprinted. As discussed herein, the separation material may in some casesserve as a green body support, so alternatively, as shown in FIG. 7,only one head 18-SG may deposit both green body support material andseparation material. As shown in FIG. 4, from bottom to top (in thiscase, 3D printing is performed from the bottom up), in these exemplaryprocesses the first layer printed is a raft separation layer or slidingrelease layer SL1 printed from, e.g., the separation material depositionhead 18-SG. The separation material may be, as noted herein, of similardebinding materials to the model material, but, e.g., with a ceramic orother spherical powder filler (e.g., particulate) that does not sinter,melt, or otherwise bind at the sintering temperature of the modelmaterial. Consequently, the separation material may have its debindingmaterial completely removed by solvent, catalysis, pyrolysis, leavingbehind a dispersible and/or removable powder (e.g., after sintering, thepowder of the separation material remaining unsintered even after thesintering process). “Separation” and “release” are generally usedinterchangeably herein.

FIGS. 5A-5D show selected sections through FIG. 4 for the purpose ofdiscussing printing and other process steps. It should be noted that theFigures are not necessarily to scale. In particular, very smallclearances or material-filled clearances (e.g., separation or releaselayers) or components (e.g., protrusions for snap removal) may be shownat exaggerated scales for the purpose of clear explanation. Moreover, itshould also be noted that in some cases, solid bodies are shown tosimplify explanation, but the internal structure of the solid bodiesherein may be 3D printed with infill patterns (e.g., honeycombs) and/ormay include chopped, short, long, or continuous fiber reinforcement asdiscussed in the CFF Patent Applications.

As shown in FIGS. 4 and 5A, upon an optionally removable andtransportable, optionally ceramic build plate 16, a raft separationlayer SL1 is printed to permit a raft RA1 printed above to be readilyremoved from the build plate 16, in some cases before debinding, or insome cases when the (e.g., portable) build plate 16 itself is stillattached through the debinding process (in the example shown in FIG. 7).

As shown in FIGS. 4 and 5B, following the printing of the raftseparation layer SL1, a raft or shrinking platform RA1 of model material(e.g., metal-bearing composite) is printed. The raft or shrinkingplatform RA1 is printed, e.g., for a purpose of providing a continuousmodel material foundation or material interconnection among the part andits supports, so that the process of mass transport and shrinking duringsintering is uniformly carried out about a common centroid or center ofmass. The raft RA1 may serve other purposes—e.g., improving earlyadhesion, clearing environmentally compromised (e.g., wet, oxidized)material from a supply path, or conditioning printing nozzles or otherpath elements (e.g., rollers), etc. As noted, two general classes ofsupports may be used: green body supports (which support the part beingprinted during the printing process, but are removed before or duringsintering) and sintering (e.g., shrinking) supports (which support thepart being sintered during the sintering process). Some supports mayserve both roles. As shown in FIGS. 4 and 5B, should an upper portion ofthe entire print benefit from green body supports, the lower layers ofgreen body supports GS1 may be printed upon either the build plate 16,or as shown in FIGS. 4 and 5B, upon the separation layer SL1 and/or theraft or shrinking platform RA1.

As shown in FIGS. 4 and 5C, subsequently, the raft RA1 may be continuedinto a surrounding or lateral shell support structure SH1 (eithercontiguously or via a parting line PL and/or physical separationstructure, e.g., a pinched and/or wasp-waisted and/or perforated orotherwise weakened cross-section that may be flexed to break away).Further, separation structures—in this case model material protrusionsP1 as well as an optionally intervening separation layer SL2—may beprinted between the raft RA1 and shell SH1 to permit the removal of theraft RA1 and shell SH1 subsequent to sintering. The printing of greenbody supports GS1 is continued, in this case providing printing supportto angled (e.g., 10-45 degrees from vertical), sparse and/or branchingsintering (e.g., shrinking) supports SS1 printed to later providesintering support for an overhanging or cantilevered portion OH1, aswell as building up a green body support GS1 for printing support forthe same overhanging or cantilevered portion OH1. “Printing support” maymean support vs. printing back pressure or gravity during printing,while “sintering support” may mean support vs. gravity, support vs.other external/internal stress during sintering, or providinginterconnections facilitating evenly distributed mass transport and/oratomic diffusion. Although an overhanging or cantilevered portion OH1 isshow in FIG. 4, an unsupported span, even if contiguous to the part P1at two opposing sides, may also benefit from supports as described.

As shown in FIGS. 4 and 5D, the surrounding shell support structure SH1is continued printing in layers, and optionally interconnectedvertically or diagonally to the part 14 via, e.g., protrusions P1 ofmodel material connected to the shell support structure SH1, and/orseparation layer material SL2 material. The parting lines and separationstructures similarly are continued vertically. An internal volume V1 inthe part P1, in this case a cylindrical volume V1, is printed with greenbody supports GB2—if the model material is sufficiently viscous orshape-retaining during printing, the 3D printing process may bridge gapsor diagonally stack, and internal volumes with sloping walls orarch-like walls may not require sintering supports. Alternatively, theinternal volume V1 is printed with sintering supports, or a combinationof green body supports and sintering supports, e.g., as with thesupports below overhang OH1. The internal volume V1 is printed with achannel to the outside of the part to permit support material to beremoved, cleaned away, or more readily accessed by heat transfer orfluids or gasses used as solvents or catalysis. The green body supportsGS1 and branching sintering supports SS1 are similarly continued tolater provide sintering support for an overhanging or cantileveredportion OH1, as well as building up a green body support GS1 forprinting support for the same overhanging or cantilevered portion OH1.

As shown in FIGS. 4 and 5D, an overhang or cantilevered portion OH1 maybe supported by sintering supports SS1 at an angle, so long as thesintering supports are self-supporting during the printing process e.g.,either by the inherent stiffness, viscosity, or other property of themodel material as it is printed in layers stacking up at a slight offset(creating the angle), or alternatively or in addition with the lateraland vertical support provided by, e.g., the green body supports GS1. Thesintering supports must also be robust to remain integral with the part14 or supporting the part 14 through the sintering process.

Finally, as shown in FIG. 4, the remainder of the part 14, support shellstructure SH1, sintering (e.g., shrinking) supports SS1, and green bodysupports GS1, GS2 are printed to completion. As printed, essentially allportions of the part 14 are supported in a vertical direction either viagreen body supports GS1, GS2, sintering (e.g., shrinking) supports SS1,the raft RA1, separation layer SL1 and/or SL2. Portions of the part 14,or structures within the part 14 that are self-supporting (because,e.g., of the material properties of the model material composite, orexternal bodies providing support, and/or those which are sufficientlystiff during support removal, debinding, and/or sintering) need not besupported vs. gravity. In addition, the support structures SS1, the raftRA1, and/or the shell structure SH1 are interconnected with modelmaterial to the part 14 in a manner that tends to shrink duringsintering about a same centroid or center of mass or at least maintainrelative local scale with respect to the neighboring portion of the part14. Accordingly, during the approximately 20% uniform shrinking of thesintering process, these support structures shrink together with thepart 14 and continue to provide support vs. gravity.

FIG. 6 shows a variation of the 3D printer, printing method, partstructure, and materials of FIG. 4. In FIG. 6, no separate green bodysupport deposition head 18 c is provided. Accordingly, green bodysupports and separation layers are formed from the same material—e.g.,the composite material used for separation layers, in which a ceramic orhigh-temperature metal particles or spheres are distributed in an, e.g.,two-stage debindable matrix. In this case, the green body supports arenot necessarily removed during or before debinding or in a separateprocess, but are instead simply weakened during debinding and, as withthe separation layers, have their remaining polymer material pyrolizedduring sintering. The remaining ceramic powder can be cleaned out and/orremoved following sintering, at the same time as the separation layers.

FIG. 7 shows one overall schematic of the process. Initially, in the 3Dprinting phase, the part 14, together with its green body supports,sintering supports, and separation layers, is printed in a 3D printer asdescribed. The green body, including all of these, optionally stillbound to a ceramic or other material build plate 16, is transferred to adebinding chamber (optionally, the debinding chamber is integrated inthe 3D printer or vice versa). As noted, if the green body supports aremade of a different polymer or substance than the first stage debindingmaterial, a separate process may remove the green body supports beforedebinding. If the green body supports are made from either the same orsimilar substances as the first stage debinding material, or one thatresponds to the debinding process by decomposing or dispersing, thegreen body supports may be removed during debinding. Accordingly, asshown in FIG. 7, debinding includes removing a first binder componentfrom the model material using a thermal process, a solvent process, acatalysis process, or a combination of these, leaving a porous brownbody structure (“DEBINDING”), and may optionally include dissolving,melting, and/or catalyzing away the green body supports (“SUPPORTREMOVAL 1”).

Continuing with FIG. 7, as shown, a brown body is transferred to asintering chamber or oven (optionally combined with the printer and/ordebinding chamber). The brown body includes the part, optionally asurrounding shell structure, and optionally sintering supports. Asnoted, the surrounding shell structure and sintering (e.g., shrinking)supports are different aspects of sintering support structure.Optionally, intervening between the shell structure and/or sinteringsupports are separation layers, formed from, e.g., the separationmaterial. Optionally, intervening between the shell structure and/orsintering supports are protrusions or ridges of model materialinterconnecting these to the part. Optionally, the same or a similarseparation material intervenes between the brown body and the buildplate. During sintering, the brown body uniformly shrinks byapproximately 20%, closing internal porous structures in the brown bodyby atomic diffusion. The second stage debinding component of the modelmaterial may be pyrolised during sintering (including, for example, withthe assistance of catalyzing or other reactive agents in gas orotherwise flowable form).

As shown in FIG. 7, a sintered body can be removed from the sinteringoven. The supporting shell structure and the sintering supports can beseparated or broken up along parting lines, and/or along separationlayers, and or by snapping or flexing protrusion connections, tacks orother specifically mechanically weak structures. The separation layersare powderized and are readily removed. Should the green body supportsbe formed from the separation material, the green body supports aresimilarly powderized and may be readily removed.

FIG. 8 shows a variation of a part printed as in FIG. 4. The part shownin FIG. 8 includes four overhanging or cantilevered sections OH2-OH5.Overhang OH2 is a lower, thicker overhang under a cantilevered, thinneroverhang OH3. While the lower overhang OH2 may in some cases be printedwithout sintering supports or even green-body supports as aself-supporting cantilever, it is below the long cantilever overhangOH3, which is sufficiently long, thin, and heavy that it may requireboth green body supports and sintering supports. Overhang OH4 is adownward-leaning overhang, which must be printed with green bodysupports (because its lowest portion is otherwise unsupported, i.e., infree space, during printing) and in a form difficult to remove sinteringsupports printed beneath without drafting or parting lines (becauserigid sintering supports would become locked in). Overhang OH5 is acantilever including a heavy block of model material, which may requireboth green body and sintering support. In addition, the part shown inFIG. 8 includes an internal cylindrical volume, from which any necessarysintering supports must be removed via a small channel. For reference,the 3D shape of the part 14 of FIG. 8 is shown in FIGS. 12 and 13.

As shown in FIG. 8, in contrast to the sintering supports SS1 of FIGS. 4and 6, sintering (e.g., shrinking) supports SS2, supporting overhangsOH2 and OH3, may be formed including thin walled, vertical members. Thevertical members of sintering supports SS2 may be independent (e.g.,vertical rods or plates) or interlocked (e.g., accordion or meshstructures). As shown in FIG. 8, the sintering supports SS2 (or indeedthe sintering supports SS1 of FIGS. 4 and 6, or the sintering supportsSS3, SS4, and SS5 of FIG. 8) may be directly tacked (e.g., contiguouslyprinted in model material, but with relatively small cross-sectionalarea) to a raft RA2, to the part 14 a, and/or to each other. Conversely,the sintering supports SS2 may be printed above, below, or beside aseparation layer, without tacking. As shown, the sintering supports SS2are removable from the orthogonal, concave surfaces of the part 14 a.

Further, as shown in FIG. 8, similar sintering (e.g., shrinking)supports SS3 are printed beneath the downward-leaning overhang OH4, andbeneath heavier overhang OH5. In order that these supports SS3, may bereadily removed, some or all are printed with a parting line PL, e.g.,formed from separation material, and/or formed from a mechanicallyweakened separation structure (e.g., printing with a nearly or barelyabutting clearance as described herein, or printing with a wasp-waisted,pinched, or perforated cross-section, or the like), or a combination ofthese (or, optionally, a combination of one or both of these with greenbody support material having little or no ceramic or metal content,should this be separately printed). These material or mechanicalseparation structures, facilitating removal of the sintering supports,may be similarly printed into the various sintering supports shown inFIGS. 4-7, 9, and throughout.

In addition, as shown in FIG. 8, sintering (e.g., shrinking) supportsSS5 are printed within the internal volume V2. The sintering supportsSS5 are each provided with multiple parting lines, so that the sinteringsupports in this case can be broken or fall apart into partssufficiently small to be readily removed, via the channel connecting theinternal volume V2. As shown, the channel CH2 itself is not printed withinternal supports, as an example of a small-diameter hole of sufficientrigidity during both printing and sintering to hold its shape. Ofcourse, supports may be printed of either or both types to ensure shaperetention.

FIG. 9 is substantially similar to FIG. 8, but shows some variations instructure. For example, beneath overhang OH3, a monolithic, form-fittingshell SH3 is printed of model material, separated from the part 14 byeither release or separation layers SL2 and/or protrusions P1. Themonolithic shell SH3 has small open cell holes throughout to lowerweight, save material, and improve penetration or diffusion of gases orliquids for debinding. This shell SH3 may surround the part 14 ifsufficient parting lines or release layers are printed into the shellSH3 (e.g., instead of the structures SH4 and SH5 to the left of thedrawing, a similar structure would be arranged), and if sufficientlyform following, act as a workholding piece.

In another example in FIG. 9, monolithic (e.g., lateral) support (e.g.,shrinking) shell SH4 is printed integral with the raft RA2, but with aparting line PL angled to draft and permit removal of the support shellSH4. In a further example shown in FIG. 9, support shell SH4 is printedangled upward (to save material) and with a large cell or honeycombinterior to lower weight, save material, and/or improve penetration ordiffusion of gases or liquids for debinding.

FIG. 9 also shows examples of continuous fiber layers deposited by,e.g., continuous fiber head 10. Sandwich-panel reinforcement layers CSP1are positioned at various layers, e.g., within upper and lower bounds ofoverhangs OH2, OH3, and OH5.

As noted, in one example, green body supports may optionally be printedfrom a matrix of thermal, soluble, or catalytic debindable compositematerial (e.g., catalytic including Polyoxymethylene—POM/acetal) andhigh melting point metal (e.g., molybdenum) or ceramic spheres, andleave behind a powder when debound. In another example, green bodysupports are printed from a thermal, soluble, pyrolytic or catalyticallyresponsive material (e.g., polymer or polymer blend) and leave behindonly removable byproducts (gases or dissolved material) when the greenbody supports are removed. The green body supports may be formed to bemechanically or chemically or thermally removed before or afterdebinding, but preferably are also made from thermal, soluble, pyrolyticor catalytically responsive material, and may be fully removed duringthe debinding stage (or immediately thereafter, e.g., subsequent powdercleaning to remove remainder powder). In some cases, the green bodysupports are removed by a different chemical/thermal process from thedebinding, before or after debinding.

An exemplary catalytically debindable composite material including POMor acetal is one example of a two-stage debinding material. In somecases, in a two-stage debinding material, in a first stage a firstmaterial is removed, leaving interconnected voids for gas passage duringdebinding. The first material may be melted out (e.g., wax),catalytically removed (e.g., converted directly into gas in a catalyticsurface reaction), or dissolved (in a solvent). A second stage binder,e.g., polyethylene, that is not as responsive to the first materialprocess, remains in a lattice-like and porous form, yet maintaining theshape of the 3D printed object awaiting sintering (e.g., before themetal or ceramic balls have been heated to sufficient temperature tobegin the atomic diffusion of sintering). This results in a brown part,which includes, or is attached to, the sintering supports. As the partis sintered at high heat, the second stage binder may be pyrolised andprogressively removed in gaseous form.

Sintering supports may be formed in blocks or segments with at leastsome intervening release layer material, so as to come apart duringremoval. Untacked sintering supports may be formed from the modelmaterial, i.e., the same composite material as the part, but separatedfrom the part to be printed by a release layer, e.g., a highertemperature composite having the same or similar binding materials. Forexample, for most metal printing, the release layer may be formed from ahigh temperature ceramic composite with the same binding waxes,polymers, or other materials. The release layer may be very thin, e.g.,one 3D printing layer. When the metal is sintered, the releaselayer—having already had a first stage binder removed—is essentiallypowderized as the temperature is insufficient to sinter or diffusionbond the ceramic material. This enables the untacked sintering supportsto be easily removed after sintering.

Tacked sintering supports may be similarly formed from the modelmaterial, i.e., the same composite material as the part, but may connectto the part either by penetrating the release layer or without a releaselayer. The tacked sintering supports are printed to be contiguous withthe part, via thin connections, i.e., “tacked” at least to the part. Thetacked sintering supports may in the alternative, or in addition, beprinted to be contiguous with a raft below the part which interconnectsthe part and the supports with model material. The raft may be separatedfrom a build plate of a 3D printer by a layer or layers of release layermaterial.

A role of tacked and untacked of sintering supports is to providesufficient supporting points versus gravity to prevent, or in some casesremediate, sagging or bowing of bridging, spanning, or overhanging partmaterial due to gravity. The untacked and tacked sintering supports areboth useful. Brown bodies, in the sintering process, may shrink byatomic diffusion uniformly about the center of mass or centroid of thepart. In metal sintering and some ceramics, typically this is at leastin part solid-state atomic diffusion. While there may be some caseswhere diffusion-based mass transport among the many interconnectedmetal/ceramic spheres does not transport sufficient material to, e.g.,maintain a very thin bridge joining large masses, this is notnecessarily the case with supports, which may be contiguously formedconnected at only one end as a one-ended bridge (or connected at twoends as two-ended bridges; or interconnected over the length).

In those cases where tacked sintering supports are tacked to, orconnected to, a model material raft upon which the part is printed, theinterconnection of model material among the tacked sintering supportsand the raft can be arranged such that the centroid of the raft-supportscontiguous body is at or near the same point in space as that of thepart, such that the part and the raft-support contiguous party eachshrink during sintering uniformly and without relative movement thatwould move the supports excessively with respect to the part. In othercases, the part itself may also be tacked to the model material raft,such that the entire contiguous body shrinks about a common centroid. Inanother variation, the part is interconnected to the raft via tackedsintering supports tacked at both ends (e.g., to the raft and to thepart) or and/along their length (e.g., to the part and/or to eachother).

In other cases, untacked sintering supports may be confined within avolume and contiguous with the raft and/or the part, the volume formedfrom model material, such that they may shrink about their own centroids(or interconnected centroid) but are continually moved through space andkept in a position supporting the part by the surrounding modelmaterial. For example, this may be effective in the case of the internalvolume V2 of FIG. 8 or 9.

In the alternative, or in addition, support or support structures orshells may be formed from model material following the form of the partin a lateral direction with respect to gravity, e.g., as shown incertain cases in FIGS. 4-9. The model material shells may be printedtacked to the base raft (which may be tacked to the part). They may beprinted integral with, but separable from the base raft. The base raftmay be separable together with the model material shells. These supportstructures may be offset from or substantially follow the lateral outercontours of the part, or may be formed from primitive shapes (straightor curved walls) but close to the part. In one variation, the supportstructures may envelop the part on all sides (in many cases, includingparting lines and/or separation structures to permit the shell to beremoved). These offset support structures may be printed with aseparation layer or layers of the separation material (optionallyceramic or another material that will transfer mechanical support butwill not be difficult to separate).

Any of the support structures discussed herein—e.g., tacked or untackedsintering supports, and/or support shells, may be printed with, insteadof or in addition to intervening separation material, a separationclearance or gap (e.g., 5-100 microns) between the part and supportstructure (both being formed from model material). In this manner,individual particles or spheres of the support structure mayintermittently contact the part during sintering, but as the separationclearance or gap is preserved in most locations, the support structuresare not printed with compacted, intimate support with the part. When andif bonding diffusion occurs at intermittently contacting particles, theseparation force required to remove the separation clearance supportstructures after sintering may be “snap-away” or “tap-away”, and in anycase far lower than an integral or contiguous extension of the part.

In an alternative, separation gaps or clearances between the part andsupport structures may be placed in partial segments following thecontour, with some of the remainder of the support structures followingthe e.g., lateral contour of the part more closely or more distantly, orboth. For example, support structures may be printed with a smallseparation gap (5-100 microns) for the majority of the supportstructure, but with other sections partially substantially following thecontour printed yet closer to the part (e.g., 1-20 microns) providingincreased rigidity and support during sintering, yet generally over aset of limited contact areas, permitting removal. This may also becarried out with large and medium gaps (e.g., 100-300 microns separationfor the larger clearance support structures, optionally with separationmaterial intervening, and 5-100 microns for the more closely followingsupport structures). Further, this may be carried out in three or morelevels (e.g., 100-300 micron gaps, 5-100 micron gaps, and 1-20 microngaps in different portions of the support structures following thecontour of the part).

Optionally, the sintering support structures may include a followingshell with an inner surface generally offset from the e.g., lateral partcontour by a larger (e.g., 5-300 microns) gap or clearance, but willhave protrusions or raised ridges extending into the gap or clearance toand separated by the smaller gap (e.g., 1-20 microns), or extendingacross the gap or clearance, to enable small point contacts between thepart and support structures formed from the same (or similar) modelmaterial. Point contacts may be easier to break off after sintering thancompacted, intimate contact of, e.g., a following contour shell.

Optionally, a neat matrix (e.g., green body supports formed from one ormore of the binder components) support structure may be printed betweenmodel material (e.g., metal) parts and model material (e.g., metal)support structures to maintain the shape of the part and structuralintegrity during the green and brown states, reducing the chance ofcracking or destruction in handling.

While several of the Figures are shown in side, cross section view, FIG.10 shows the sintered body structure of FIG. 4 in top views, while FIG.11 shows a variation for the purpose of explanation. As shown, supportshells or other structures may be printed with separation or partinglines or layers between portions of the support structure. Theseparation or parting lines or layers may be any separation structuredescribed herein, including those described between the part and supportstructure. For example, the separation lines or layer permitting asupport shell to be broken into two or more parts (optionally manyparts) may be formed from separation material (e.g., ceramic andbinder), from binder material, from model material (e.g., metal) withseparation gaps (such as 1-20, 5-100, or 50-300 microns) and/orprotrusions or ridges permitting snap-off structures. For example, asupport structure or shell may be formed to be split in two halves(e.g., as in FIG. 10), creating a parting line in the support structureor shell. Parting lines are optionally printed to be contiguous within aplane intersecting (e.g., bisecting) a support shell structure so as topermit ready separation. Multiple planes of parting lines may intersectthe support shell structure.

In the case of complex geometries, as noted above, support structuresmay be printed with parting lines, sectioned into smaller subsections(e.g., as PL-1 in FIG. 11, like orange slices, or further sectioned inan orthogonal axis such that they can be easily removed), as shown inFIG. 11. For example, if support structures are printed filling in adovetail of a part, support structures could be formed in three parts,e.g., could be designed in three parts, such that the center part eitherhas draft or is rectangular and can be easily removed, thereby freeingup the two side parts to slide inward and then be removed. Conversely,parting lines may be printed to be interlocking (e.g., PL-3 in FIG. 11),crenellated or formed as a box joint (e.g., similar to PL-3 in FIG. 11),so as to resist separation, in some cases other than in a transversedirection. Parting lines may be printed nearly almost cut through thesupport shell (e.g., PL-2 in FIG. 11). Note that FIG. 11 is depictedwithout protrusions P1, i.e., with only separation layers SL2 in thevertical direction, and largely monolithic, surrounding support shellSH.

In some cases, particularly in the case of a small number of partinglines (e.g., halves, thirds, quarters) the support structures, at leastbecause they are form following structures, may be preserved for lateruse as a workholding fixture, e.g., soft jaws, for holding a sinteredthe part in secondary operations (such as machining). For example, if asupport structure were to support a generally spherical part, a supportstructure suitable for later use as a workholding jaw or soft jaw, thestructure should retain the part from all sides, and therefore extendpast the center or half-way point of the sphere. For the purposes ofsintering and supporting vs. gravity, the support structure need notextend past the halfway point (or slightly before), but for the purposesof subsequent workholding for inspection and post processing, thesupport structure would continue past the half way point (e.g. up to ⅔of the part's height, and in some cases overhanging the part) enablingpositive grip in, e.g., a vise.

Further, attachment features to hold the workholding fixture(s) or softjaw(s) in a vise (or other holder) may be added to the support structurefor the purpose of post processing, e.g., through holes for attachmentto a vise, or dovetails, or the like.

Alternatively, or in addition, a ceramic support may be printed, andsintered, to act as a reusable support for the sintering step of many 3Dprinted parts. In this case, upwardly facing surfaces of the reusablesupport may be printed to shrink to the same height as the matching orfacing surface of the part being supported.

As discussed herein, a feedstock material for forming the part and/orthe sintering supports may include approximately 50-70% (preferablyapprox. 60-65%) volume fraction secondary matrix material, e.g.,(ceramic or metal) substantially spherical beads or powder in 10-50micron diameter size, approximately 20-30% (preferably approx. 25%volume fraction of soluble or catalysable binder, (preferably solid atroom temperature), approximately 5-10% (preferably approx. 7-9%) volumefraction of pyrolysable binder or primary matrix material, (preferablysolid at room temperature), as well as approximately 0.1-15% (preferablyapprox. 5-10%) volume fraction of carbon fiber strands, each fiberstrand coated with a metal that does not react with carbon at sinteringtemperatures or below (e.g., nickel, titanium boride). As discussedherein, the “primary matrix” is the polymer binder and is deposited bythe 3D printer, holding the “secondary matrix” beads or spheres and thefiber filler; and following sintering, the (ceramic or metal) materialof the beads or spheres becomes the matrix, holding the fiber filler.

Alternatively, a feedstock material for forming the part and/or thesintering supports may include approximately 50-70% (preferably approx.60-65%) volume fraction secondary matrix material, e.g., (ceramic ormetal) substantially spherical beads or powder in 10-50 micron diametersize, approximately 20-30% (preferably approx. 25% volume fraction ofsoluble or catalysable binder, (preferably solid at room temperature),approximately 5-10% (preferably approx. 7-9%) volume fraction of apyrolysable binder or secondary matrix material approximately 1/10-1/200 the elastic modulus of the (ceramic or metal) secondary matrixmaterial, and approximately 0.1-15% (preferably approx. 5-10%) volumefraction of particle or fiber filler of a material approximately 2-10times the elastic modulus of the secondary, (metal or ceramic) matrixmaterial. As discussed herein, the “primary matrix” is the polymerbinder and is deposited by the 3D printer, holding the “secondarymatrix” beads or spheres and the fiber filler; and following sintering,the (ceramic or metal) material of the beads or spheres becomes thematrix, holding the particle of fiber filler.

A comparison of elastic modulus may be found in the following table,with polymer/binder primary matrices of 1-5 GPa elastic modulus

Secondary Elastic Modulus Elastic Modulus matrix (10⁹ N/m², GPa) Fill(10⁹ N/m², GPa) Steel 180-200 Carbon Fiber 200-600 Aluminum  69 GraphiteFiber 200-600 Copper 117 Boron Nitride 100-400 Titanium 110 BoronCarbide  450 Alumina 215 Silicon Carbide  450 Cobalt 209 Alumina  215Bronze  96-120 Diamond 1220 Tungsten Carbide 450-650 Graphene 1000Carbon Nanotube   1000+

The spheres, beads or powder (e.g., particulate) may be a range ofsizes. A binder may include dispersant, stabilizer, plasticizer, and/orinter-molecular lubricant additive(s). Some candidate secondarymatrix-filler combinations that may be deposited by a 3D printer withina binder or polymer primary matrix include cobalt or bronze beads withtungsten carbide coated graphite (carbon) fibers; aluminum beads withgraphite (carbon) fibers; steel beads with boron nitride fibers;aluminum beads with boron carbide fibers; aluminum beads with nickelcoated carbon fibers; alumina beads with carbon fibers; titanium beadswith silicon carbide fibers; copper beads with aluminum oxide particles(and carbon fibers); copper-silver alloy beads with diamond particles.Those fibers that may be printed via the techniques of the CFF PatentApplications may also be embedded as continuous fibers. Carbon forms forparticles or fibers include carbon nanotubes, carbon blacks,short/medium/long carbon fibers, graphite flakes, platelets, graphene,carbon onions, astralenes, etc.

Some soluble-pyrolysable binder combinations include polyethylene glycol(PEG) and polymethyl methacrylate (PMMA) (stearic acid optional, PMMA inemulsion form optional); waxes (carnauba, bees wax, paraffin) mixed withsteatite and/or polyethylene (PE); PEG, polyvinylbutyral (PVB) andstearic acid.

Some pyrolysable second stage binders include: polyolefin resinspolypropylene (PP), high-density polyethylene (HDPE); linear low-densitypolyethylene (LLDPE), and polyoxymethylene copolymer (POM). As noted, Inthermal debinding, a part containing binder is heated at a given rateunder controlled atmosphere. The binder decomposes by thermal crackingin small molecules that are sweep away by the gas leaving the oven. Insolvent debinding, a part containing binder is subject to dissolving thebinder in appropriate solvent, e.g., acetone or heptane. In catalyticdebinding, the part is brought into contact with an atmosphere thatcontains a gaseous catalyst that accelerates cracking of the binder,which can be carried away.

Accordingly, the present disclosure describes a method of depositingmaterial and an apparatus for additive manufacturing. The apparatusfeeds a first filament including a binder matrix and sinterablespherized and/or powdered first material having a first sinteringtemperature along a material feed path, and feeds a second filamentincluding the binder matrix and sinterable spherized and/or powderedsecond material having a second sintering temperature higher than thefirst sintering temperature (optionally, e.g., more than 500 degrees C.higher). The apparatus forms layers of second material by depositionupon a build plate or prior deposition of first or second material, andlayers of first material by deposition upon prior deposition of secondmaterial. The apparatus (including an additional station of theapparatus) debinds at least a portion of the binder matrix from each ofthe first material and second material. The apparatus (including anadditional station of the apparatus) then heats a part so formed fromfirst and second material to the first sintering temperature, therebysintering the first material and decomposing the second material. Inprinting a sinterable part using a 3D printing model material includinga binder and a ceramic or metal sintering material, a release layerintervenes between support structures and the part, each of the supportstructures and the part formed of the model material or composite. Therelease layer includes a spherized or powdered higher meltingtemperature material—ceramic or high temperature metal for example,optionally deposited with a similar (primary) matrix or binder componentto the model material. After sintering, the release layer may become aloose powder, permitting the supports to be easily removed.

In the present disclosure, “3D printer” is inclusive of both discreteprinters and/or toolhead accessories to manufacturing machinery whichcarry out an additive manufacturing sub-process within a larger process.A 3D printer is controlled by a motion controller 20 which interpretsdedicated G-code and drives various actuators of the 3D printer inaccordance with the G-code.

“Fill material” includes material that may be deposited in substantiallyhomogenous form as extrudate, fluid, or powder material, and issolidified, e.g., by hardening, crystallizing, or curing. “Substantiallyhomogenous” includes powders, fluids, blends, dispersions, colloids,suspensions and mixtures.

“3D printer” meaning includes discrete printers and/or toolheadaccessories to manufacturing machinery which carry out an additivemanufacturing sub-process within a larger process. A 3D printer iscontrolled by a motion controller 20 which interprets dedicated G-code(toolpath instructions) and drives various actuators of the 3D printerin accordance with the G-code.

“Deposition head” may include jet nozzles, spray nozzles, extrusionnozzles, conduit nozzles, and/or hybrid nozzles.

“Filament” generally may refer to the entire cross-sectional area of a(e.g., spooled) build material.

What is claimed is:
 1. A method of reducing distortion in an additivelymanufactured part, comprising: depositing, in successive layers, ashrinking platform formed from a composite, the composite includingmetal particles embedded in a first matrix; depositing shrinkingsupports of the composite upon the shrinking platform; forming, in atleast one shrinking support, a separation clearance dividing the atleast one shrinking support into fragments; depositing, from thecomposite, a part upon the shrinking platform and shrinking supports;depositing a separation material intervening between the part and theshrinking supports, the separation material including a ceramic powderand a second matrix; and forming, from the shrinking platform, shrinkingsupports, separation material, and part, a portable platform assembly ina green state, wherein the shrinking support is configured to preventthe portable platform assembly from distorting from gravitational forceduring sintering of the metal particles of the portable platformassembly in a brown state, and wherein the ceramic powder of theseparation material is configured to separate the shrinking support fromthe part following sintering.
 2. The method according to claim 1,wherein the shrinking platform interconnects the shrinking supports withone another, and wherein the method further comprises: maintaining, withthe first matrix and second matrix, a shape of the portable platformassembly during deposition; debinding the first matrix in the portableplatform assembly from the green state to the brown state, in a firstcommon chamber; transporting the portable platform assembly in the brownstate to a second common chamber for sintering; sintering the portableplatform assembly in the brown state to shrink at a rate uniformthroughout as neighboring metal particles throughout the shape-retainingbrown part assembly undergo atomic diffusion, and during sintering inthe second common chamber, decomposing the second matrix to leave theceramic powder loose via the heat of the sintering; maintaining, withthe first matrix, a shape of the portable platform assembly during atleast part of the sintering; and maintaining, with the ceramic powder,the shrinking supports separate from the part.
 3. The method accordingto claim 1, wherein the separation clearance is formed as a verticalclearance separating neighboring shrinking supports and extending forsubstantially a height of the neighboring shrinking supports, andwherein the method further comprises: separating the neighboringshrinking supports from one another along the vertical clearance.
 4. Themethod according to claim 1, wherein the first matrix and the secondmatrix are at least partially debindable by a common debinder.
 5. Themethod according to claim 1, wherein forming the separation clearancecomprises forming the fragments as blocks separable from one anotheralong the separation clearance contiguous within a plane intersectingthe shrinking supports.
 6. The method according to claim 1, whereindepositing shrinking supports comprises forming a lateral support shellof the composite as the shrinking supports to follow a lateral contourof the part.
 7. The method according to claim 6, further comprising:connecting the lateral support shell to the lateral contour of the partby forming separable attachment protrusions of the composite between thelateral support shell and the part.
 8. The method according to claim 6,further comprising: dividing the lateral support shell into shellfragments; debinding the first matrix sufficient to form a portableassembly in the brown state including the shrinking platform, shrinkingsupports, lateral support shell, and part; separating the lateralsupport shell into the shell fragments; and separating the shellfragments from the part.
 9. The method according to claim 1, furthercomprising: depositing the separation material to intervene at anon-horizontal surface of the part opposing a surface of the shrinkingsupports, the non-horizontal surface of the part including at least oneof a vertical surface, a curved surface, and a surface angled withrespect to horizontal.
 10. The method according to claim 1, furthercomprising: providing a sliding powder layer below the shrinkingplatform, of equal or larger surface area than a bottom of the shrinkingplatform, the sliding powder layer configured to reduce lateralresistance between the shrinking platform and an underlying surfaceduring sintering.
 11. A method of reducing distortion in an additivelymanufactured part, comprising: depositing, in successive layers, ashrinking platform formed from a composite, the composite includingmetal particles, a first binder component, and a second bindercomponent; depositing, from the composite, a part supported by theshrinking platform, the shrinking platform forming a foundation thatholds the part and is configured, during shrinking of the composite, toprevent movement of the shrinking platform versus the part; depositing afirst shrinking support of the composite upon a first portion of thepart and supporting a second portion of the part; depositing aseparation material intervening between the part and the first shrinkingsupport, the separation material including a ceramic powder and a thirdbinder component, wherein the third binder component is responsive to asame debinder as the first binder component; forming, in the firstshrinking support, a separation clearance dividing the first shrinkingsupport into fragments separable along the separation clearance; andforming the shrinking platform, first shrinking support, separationmaterial, and part as a portable platform assembly in a green state,wherein the first binder component and third binder component areconfigured to maintain a shape of the portable platform assembly duringdepositing of the portable platform assembly, wherein the firstshrinking support is configured to prevent the portable platformassembly from distorting from gravitational force during sintering ofthe metal particles of the portable platform assembly in a brown state,and wherein the separation material is configured to separate the firstshrinking support from the part during sintering and powderize to permitthe first shrinking support to be removed from the part after sintering.12. The method according to claim 11, further comprising: depositingsecond shrinking supports of the composite upon the shrinking platform,wherein the shrinking platform interconnects the shrinking supports withone another; and depositing the separation material intervening betweenthe part and the second shrinking supports, wherein the second shrinkingsupports are included in the portable platform assembly in the greenstate, and the ceramic powder of the separation material is configuredto separate the second shrinking support from the part followingsintering.
 13. The method according to claim 11, further comprising:depositing the separation material intervening directly between the partand the shrinking platform, wherein the ceramic powder of the separationmaterial is configured to separate the part from the shrinking platformfollowing sintering.
 14. The method according to claim 11, furthercomprising: maintaining, with the first binder component and secondbinder component, a shape of the portable platform assembly duringdeposition; debinding the first binder component in the platformassembly from a green state to a brown state, in a first common chamber;transporting the portable platform assembly in the brown state to asecond common chamber; sintering, in the second common chamber, theportable platform assembly in the brown state to shrink at a rateuniform throughout as neighboring metal particles throughout theshape-retaining brown part assembly undergo atomic diffusion and thesecond binder decomposes in the heat of sintering; and decomposing thethird binder component to leave the ceramic powder loose in the secondcommon chamber.
 15. The method according to claim 11, wherein theseparation clearance is formed as a vertical clearance extending forsubstantially a height of the first shrinking support, and wherein themethod further comprises separating the fragments from one another alongthe vertical clearances.
 16. The method according to claim 11, whereinforming the separation clearance comprises forming the fragments asblocks separable from one another along a separation clearancecontiguous within a plane intersecting the first shrinking support. 17.The method according to claim 11, wherein depositing the first shrinkingsupport comprises forming a lateral support shell of the same compositeas the first shrinking support to follow a lateral contour of the part.18. The method according to claim 17, further comprising: dividing thelateral support shell into shell fragments; and separating the shellfragments from the part.
 19. The method according to claim 11, whereindepositing the separation material comprises depositing the separationmaterial to intervene at a non-horizontal surface of the part opposing asurface of the first shrinking support, the non-horizontal surface ofthe part including at least one of a vertical surface, a curved surface,and a surface angled with respect to horizontal.
 20. The methodaccording to claim 11, further comprising: providing a sliding powderlayer below the shrinking platform, of equal or larger surface area thana bottom of the shrinking platform, the sliding powder layer configuredto reduce lateral resistance between the shrinking platform and anunderlying surface during sintering.
 21. A method of reducing distortionin an additively manufactured part, comprising: feeding a compositeincluding metal particles, a first binder and a second binder; feeding aseparation material including ceramic powder and a third binder;depositing a portable platform assembly formed from the composite in agreen state, the portable platform assembly including a shrinkingplatform, first shrinking supports, second shrinking supports,separation material and a part, the shrinking platform interconnectingthe first shrinking supports with one another, the part deposited uponthe first shrinking supports, the second shrinking supports supportingan upper portion of the part upon a lower portion of the part, and theseparation material separating the part from the first shrinkingsupports and the second shrinking supports; maintaining a shape of theportable platform assembly during deposition with the first binder,second binder, and third binder; forming a separation clearance duringdeposition dividing at least one of the second shrinking supports intofragments; debinding the first binder to debind the platform assemblyfrom a green state to a brown state; and sintering the platform assemblyin the brown state to shrink at a rate uniform throughout the portableplatform assembly as interconnected by the shrinking platform, and todecompose the second binder and the third binder, wherein the relativeshape of the platform assembly is maintained versus gravitational forceby the first shrinking supports and the second shrinking supports, andwherein the third binder is decomposed during sintering to powderize theseparation material leaving a loose ceramic powder separating the partfrom the first shrinking supports and the second shrinking supports. 22.The method according to claim 21, further comprising: depositing theseparation material in the portable platform assembly interveningdirectly between the part and the shrinking platform, wherein the looseceramic powder separates the part from the shrinking platform followingsintering.
 23. The method according to claim 21, wherein forming theseparation clearance comprises forming the separation clearance as avertical clearance extending for substantially a height of the at leastone second shrinking support, and wherein the method further comprisesseparating the fragments from one another along the vertical clearances.24. The method according to claim 21, wherein forming the separationclearance comprises forming the fragments as blocks separable from oneanother along the separation clearance contiguous within a planeintersecting the first shrinking support.
 25. The method according toclaim 21, further comprising: forming a lateral support shell of thesame composite as the first shrinking support to follow a lateralcontour of the part.
 26. The method according to claim 25, furthercomprising: dividing the lateral support shell into shell fragments; andseparating the shell fragments from the part.
 27. The method accordingto claim 21, further comprising: depositing the separation material tointervene at a non-horizontal surface of the part opposing a surface ofthe first shrinking support, the non-horizontal surface of the partincluding at least one of a vertical surface, a curved surface, and asurface angled with respect to horizontal.
 28. The method according toclaim 21, further comprising: providing a sliding powder layer below theshrinking platform, of equal or larger surface area than a bottom of theshrinking platform, that reduces lateral resistance between theshrinking platform and an underlying surface during sintering.
 29. Themethod according to claim 28, wherein the underlying surface comprises aportable build plate, and wherein the method further comprises: formingthe shrinking platform above the portable build plate; forming thesliding powder layer below the shrinking platform and above the portablebuild plate with the release material; and keeping the portable platformassembly together with the portable build plate as a unit duringdeposition, debinding, and sintering.
 30. The method according to claim21, wherein the metal particles in the composite are distributed in atleast two sizes.